1
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Contesse T, Gomes-Ribeiro J, Royon L, Fofo H, Braine A, Glangetas C, Zhang S, Barbano MF, Soiza-Reilly M, Georges F, Barik J, Fernandez SP. Social stress increases anxiety by GluA1-dependent synaptic strengthening of ventral tegmental area inputs to the basolateral amygdala. Biol Psychiatry 2025:S0006-3223(25)01121-7. [PMID: 40245975 DOI: 10.1016/j.biopsych.2025.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2024] [Revised: 03/17/2025] [Accepted: 04/06/2025] [Indexed: 04/19/2025]
Abstract
BACKGROUND Brain defensive mechanisms evolved to maintain low levels of state anxiety. However, risk factors such as stress exposure shifts activity within defensive circuits, resulting in increased anxiety. The amygdala is a crucial node for maintaining adaptive anxiety levels, and amygdala hyperactivity can lead to pathological anxiety through mechanisms that are not well understood. METHODS We used chronic social defeat stress (CSD) in mice. We combined anatomical tracing methods, patch-clamp recordings and optogenetics to probe how synaptic inputs from the ventral tegmental area (VTA) to the basolateral amygdala (BLA) are affected by CSD. We performed in vivo fiber photometry recordings to track inputs onto basolateral amygdala. Array tomography and electron microscopy were used to unravel the structural composition of VTA-BLA synapses. RESULTS We identified the VTA as a source of glutamatergic inputs to the BLA potentiated by stress. In turn, inputs from mPFC were not potentiated. BLA-projecting VTA glutamatergic neurons are activated by social stress, increasing their excitability and synaptic strength. In vivo potentiation of VTA glutamatergic inputs in the BLA is sufficient to increase anxiety. We showed that stress-induced synaptic strengthening is mediated by insertion of GluA1-containing AMPA receptors. Impeding GluA1 subunit trafficking in BLA neurons with VTA upstream inputs prevents stress-induced increase in synaptic firing and anxiety. CONCLUSIONS Potentiation of VTA inputs increases synaptic integration, enhancing amygdala activity and promoting maladaptive anxiety. Understanding the impact of amygdala hyperactivity could lead to targeted therapies, restoring circuit balance and offering new precision medicine approaches for anxiety disorders.
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Affiliation(s)
- Thomas Contesse
- Université Côte d'Azur, Nice, France; Institut de Pharmacologie Moléculaire & Cellulaire, CNRS UMR7275, Valbonne, France; Inserm U1323
| | - Joana Gomes-Ribeiro
- Université Côte d'Azur, Nice, France; Institut de Pharmacologie Moléculaire & Cellulaire, CNRS UMR7275, Valbonne, France; Inserm U1323
| | - Lea Royon
- Université Côte d'Azur, Nice, France; Institut de Pharmacologie Moléculaire & Cellulaire, CNRS UMR7275, Valbonne, France; Inserm U1323
| | - Hugo Fofo
- Université Côte d'Azur, Nice, France; Institut de Pharmacologie Moléculaire & Cellulaire, CNRS UMR7275, Valbonne, France; Inserm U1323
| | - Anaelle Braine
- Université de Bordeaux, CNRS, IMN, UMR 5293, F-33000 Bordeaux, France
| | | | - Shiliang Zhang
- Confocal and Electron Microscopy Core, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA
| | - M Flavia Barbano
- Integrative Neuroscience Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Mariano Soiza-Reilly
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos AiresC1428EGA, Argentina
| | - François Georges
- Université de Bordeaux, CNRS, IMN, UMR 5293, F-33000 Bordeaux, France
| | - Jacques Barik
- Université Côte d'Azur, Nice, France; Institut de Pharmacologie Moléculaire & Cellulaire, CNRS UMR7275, Valbonne, France; Inserm U1323.
| | - Sebastian P Fernandez
- Université Côte d'Azur, Nice, France; Institut de Pharmacologie Moléculaire & Cellulaire, CNRS UMR7275, Valbonne, France; Inserm U1323.
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2
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Reinders NR, van der Spek SJF, Klaassen RV, Koymans KJ, MacGillavry HD, Smit AB, Kessels HW. Amyloid-β-Driven Synaptic Deficits Are Mediated by Synaptic Removal of GluA3-Containing AMPA Receptors. J Neurosci 2025; 45:e0393242024. [PMID: 39779375 PMCID: PMC11867010 DOI: 10.1523/jneurosci.0393-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 12/18/2024] [Accepted: 12/19/2024] [Indexed: 01/11/2025] Open
Abstract
The detrimental effects of oligomeric amyloid-β (Aβ) on synapses are considered the leading cause for cognitive deficits in Alzheimer's disease. However, through which mechanism Aβ oligomers impair synaptic structure and function remains unknown. Here, we used electrophysiology and amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) imaging on mouse and rat neurons to demonstrate that GluA3 expression in neurons lacking GluA3 is sufficient to resensitize their synapses to the damaging effects of Aβ, indicating that GluA3-containing AMPARs at synapses are necessary and sufficient for Aβ to induce synaptic deficits. We found that Aβ oligomers trigger the endocytosis of GluA3 and promote its translocation toward endolysosomal compartments for degradation. Mechanistically, these Aβ-driven effects critically depend on the PDZ-binding motif of GluA3. A single point mutation in the GluA3 PDZ-binding motif prevented Aβ-driven effects and rendered synapses fully resistant to the effects of Aβ. Correspondingly, proteomics on synaptosome fractions from APP/PS1-transgenic mice revealed a selective reduction of GluA3 at an early age. These findings support a model where the endocytosis and lysosomal degradation of GluA3-containing AMPARs are a critical early step in the cascade of events through which Aβ accumulation causes a loss of synapses.
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Affiliation(s)
- Niels R Reinders
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam 1105 BA, The Netherlands
- Swammerdam Institute of Life Sciences, Amsterdam Neuroscience, University of Amsterdam, Amsterdam 1098 XH, The Netherlands
- Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam 1081 HV, The Netherlands
- Division of Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Sophie J F van der Spek
- Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Remco V Klaassen
- Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Karin J Koymans
- Swammerdam Institute of Life Sciences, Amsterdam Neuroscience, University of Amsterdam, Amsterdam 1098 XH, The Netherlands
| | - Harold D MacGillavry
- Division of Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - August B Smit
- Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam 1081 HV, The Netherlands
| | - Helmut W Kessels
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam 1105 BA, The Netherlands
- Swammerdam Institute of Life Sciences, Amsterdam Neuroscience, University of Amsterdam, Amsterdam 1098 XH, The Netherlands
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3
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Brown JC, Hell JW, Gerges NZ. BRAG about (s)lots. J Cell Biol 2023; 222:e202310023. [PMID: 37938213 PMCID: PMC10631466 DOI: 10.1083/jcb.202310023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023] Open
Abstract
Mutations in IQSEC2/BRAG1 cause intellectual dysfunction by impairing ARF-GEF activity and long-term depression. In this issue, Bai et al. (https://doi.org/10.1083/jcb.202307117) discover how constitutive ARF-GEF activity is regulated by a closed conformation which opens in the presence of Ca2+. Two known pathogenic mutations cause "leaky" autoinhibition with reduced synaptic dynamic range and impaired cognitive performance.
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Affiliation(s)
- Joshua C. Brown
- Division of Depression and Anxiety Disorders, Brain Stimulation Mechanisms Laboratory, McLean Hospital, Belmont, MA, USA
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Johannes W. Hell
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, USA
| | - Nashaat Z. Gerges
- Biopharmaceutical Sciences Department, School of Pharmacy, Medical College of Wisconsin, Milwaukee, WI, USA
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4
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Elwyn R, Mitchell J, Kohn MR, Driver C, Hay P, Lagopoulos J, Hermens DF. Novel ketamine and zinc treatment for anorexia nervosa and the potential beneficial interactions with the gut microbiome. Neurosci Biobehav Rev 2023; 148:105122. [PMID: 36907256 DOI: 10.1016/j.neubiorev.2023.105122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 03/04/2023] [Accepted: 03/07/2023] [Indexed: 03/13/2023]
Abstract
Anorexia nervosa (AN) is a severe illness with diverse aetiological and maintaining contributors including neurobiological, metabolic, psychological, and social determining factors. In addition to nutritional recovery, multiple psychological and pharmacological therapies and brain-based stimulations have been explored; however, existing treatments have limited efficacy. This paper outlines a neurobiological model of glutamatergic and γ-aminobutyric acid (GABA)-ergic dysfunction, exacerbated by chronic gut microbiome dysbiosis and zinc depletion at a brain and gut level. The gut microbiome is established early in development, and early exposure to stress and adversity contribute to gut microbial disturbance in AN, early dysregulation to glutamatergic and GABAergic networks, interoceptive impairment, and inhibited caloric harvest from food (e.g., zinc malabsorption, competition for zinc ions between gut bacteria and host). Zinc is a key part of glutamatergic and GABAergic networks, and also affects leptin and gut microbial function; systems dysregulated in AN. Low doses of ketamine in conjunction with zinc, could provide an efficacious combination to act on NMDA receptors and normalise glutamatergic, GABAergic and gut function in AN.
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Affiliation(s)
- Rosiel Elwyn
- Thompson Institute, University of the Sunshine Coast, Birtinya, QLD, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia.
| | - Jules Mitchell
- Thompson Institute, University of the Sunshine Coast, Birtinya, QLD, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
| | - Michael R Kohn
- AYA Medicine Westmead Hospital, CRASH (Centre for Research into Adolescent's Health) Western Sydney Local Health District, Sydney University, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
| | - Christina Driver
- Thompson Institute, University of the Sunshine Coast, Birtinya, QLD, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
| | - Phillipa Hay
- Translational Health Research Institute (THRI) School of Medicine, Western Sydney University, Campbelltown, NSW, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
| | - Jim Lagopoulos
- Thompson Institute, University of the Sunshine Coast, Birtinya, QLD, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
| | - Daniel F Hermens
- Thompson Institute, University of the Sunshine Coast, Birtinya, QLD, Australia; SouthWest Sydney Local Health District, Liverpool Hospital, Liverpool, NSW, Australia
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5
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Augereau K, Migues PV, Hardt O. Infusing zeta inhibitory peptide into the perirhinal cortex of rats abolishes long-term object recognition memory without affecting novel object location recognition. Front Behav Neurosci 2022; 16:1007748. [PMID: 36560931 PMCID: PMC9763881 DOI: 10.3389/fnbeh.2022.1007748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 11/07/2022] [Indexed: 12/12/2022] Open
Abstract
Infusing the amnesic agent zeta inhibitory peptide (ZIP) into the dorsal hippocampus disrupts established long-term object location recognition memory without affecting object identity recognition, which likely depends on the perirhinal cortex. Here, we tested whether infusing ZIP into the perirhinal cortex can abolish long-term memory supporting object identity recognition, leaving long-term object location recognition memory intact. We infused ZIP into the perirhinal cortex of rats either 1 day or 6 days after exposing them to two identical objects in an open field arena. One day after ZIP infusion, that is, 2 or 7 days after object exposure, we either assessed whether the animals recognized that now one of the two objects was novel or whether they recognized that one of the two familiar objects was at a new location. Our results show for both retention intervals, infusions of ZIP into the perirhinal cortex impaired novel object recognition but spared novel object location recognition. Rats that received a scrambled version of ZIP had no deficit in either test at both retention intervals and expressed stronger novel object recognition compared to rats infused with ZIP. These findings support the view that object recognition depends on dissociable memory representations distributed across different brain areas, with perirhinal cortex maintaining long-term memory for what objects had been encountered, and hippocampus supporting memory for where these objects had been placed.
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Affiliation(s)
| | | | - Oliver Hardt
- Department of Psychology, McGill University, Montréal, QC, Canada
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6
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Brown JC, Higgins ES, George MS. Synaptic Plasticity 101: The Story of the AMPA Receptor for the Brain Stimulation Practitioner. Neuromodulation 2022; 25:1289-1298. [PMID: 35088731 PMCID: PMC10479373 DOI: 10.1016/j.neurom.2021.09.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 08/10/2021] [Accepted: 09/08/2021] [Indexed: 02/04/2023]
Abstract
The fields of Neurobiology and Neuromodulation have never been closer. Consequently, the phrase "synaptic plasticity" has become very familiar to non-basic scientists, without actually being very familiar. We present the "Story of the AMPA receptor," an easy-to-understand "10,000 ft" narrative overview of synaptic plasticity, oriented toward the brain stimulation clinician or scientist without basic science training. Neuromodulation is unparalleled in its capacity to both modulate and probe plasticity, yet many are not comfortable with their grasp of the topic. Here, we describe the seminal discoveries that defined the canonical mechanisms of long-term potentiation (LTP), long-term depression (LTD), and homeostatic plasticity. We then provide a conceptual framework for how plasticity at the synapse is accomplished, describing the functional roles of N-methyl-d-aspartate (NMDA) receptors and calcium, their effect on calmodulin, phosphatases (ie, calcineurin), kinases (ie, calcium/calmodulin-dependent protein kinase [CaMKII]), and structural "scaffolding" proteins (ie, post-synaptic density protein [PSD-95]). Ultimately, we describe how these affect the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor. More specifically, AMPA receptor delivery to (LTP induction), removal from (LTD), or recycling within (LTP maintenance) the synapse is determined by the status of phosphorylation and protein binding at specific sites on the tails of AMPA receptor subunits: GluA1 and GluA2. Finally, we relate these to transcranial magnetic stimulation (TMS) treatment, highlighting evidences for LTP as the basis of high-frequency TMS therapy, and briefly touch on the role of plasticity for other brain stimulation modalities. In summary, we present Synaptic Plasticity 101 as a singular introductory reference for those less familiar with the mechanisms of synaptic plasticity.
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Affiliation(s)
- Joshua C Brown
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA; Department of Neurology, Medical University of South Carolina, Charleston, SC, USA; Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, Providence, RI, USA.
| | - Edmund S Higgins
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA
| | - Mark S George
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA; Ralph Johnson VA Medical Center, Charleston, SC, USA
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7
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Gugustea R, Jia Z. Genetic manipulations of AMPA glutamate receptors in hippocampal synaptic plasticity. Neuropharmacology 2021; 194:108630. [PMID: 34089730 DOI: 10.1016/j.neuropharm.2021.108630] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 05/06/2021] [Accepted: 05/18/2021] [Indexed: 01/17/2023]
Abstract
Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are the principal mediators of fast excitatory synaptic transmission and they are required for various forms of synaptic plasticity, including long-term potentiation (LTP) and depression (LTD), which are key mechanisms of learning and memory. AMPARs are tetrameric complexes assembled from four subunits (GluA1-4), however, the lack of subunit-specific pharmacological tools has made the assessment of individual subunits difficult. The application of genetic techniques, particularly gene targeting, allows for precise manipulation and dissection of each subunit in the regulation of neuronal function and behaviour. In this review, we summarize studies using various mouse models with genetically altered AMPARs and focus on their roles in basal synaptic transmission, LTP, and LTD at the hippocampal CA1 synapse. These studies provide strong evidence that there are multiple forms of LTP and LTD at this synapse which can be induced by various induction protocols, and they are differentially regulated by different AMPAR subunits and domains. We conclude that it is necessary to delineate the mechanism of each of these forms of plasticity and their contribution to memory and brain disorders.
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Affiliation(s)
- Radu Gugustea
- The Hospital for Sick Children, Neurosciences and Mental Health Program, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada; Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Zhengping Jia
- The Hospital for Sick Children, Neurosciences and Mental Health Program, Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada; Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
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8
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Livingstone RW, Elder MK, Singh A, Westlake CM, Tate WP, Abraham WC, Williams JM. Secreted Amyloid Precursor Protein-Alpha Enhances LTP Through the Synthesis and Trafficking of Ca 2+-Permeable AMPA Receptors. Front Mol Neurosci 2021; 14:660208. [PMID: 33867938 PMCID: PMC8047154 DOI: 10.3389/fnmol.2021.660208] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/10/2021] [Indexed: 11/13/2022] Open
Abstract
Regulation of AMPA receptor expression by neuronal activity and neuromodulators is critical to the expression of both long-term potentiation (LTP) and memory. In particular, Ca2+-permeable AMPARs (CP-AMPAR) play a unique role in these processes due to their transient, activity-regulated expression at synapses. Secreted amyloid precursor protein-alpha (sAPPα), a metabolite of the parent amyloid precursor protein (APP) has been previously shown to enhance hippocampal LTP as well as memory formation in both normal animals and in Alzheimer’s disease models. In earlier work we showed that sAPPα promotes trafficking of GluA1-containing AMPARs to the cell surface and specifically enhances synthesis of GluA1. To date it is not known whether de novo synthesized GluA1 form CP-AMPARs or how they contribute to sAPPα-mediated plasticity. Here, using fluorescent non-canonical amino acid tagging–proximity ligation assay (FUNCAT-PLA), we show that brief treatment of primary rat hippocampal neurons with sAPPα (1 nM, 30 min) rapidly enhanced the cell-surface expression of de novo GluA1 homomers and reduced levels of de novo GluA2, as well as extant GluA2/3-AMPARs. The de novo GluA1-containing AMPARs were localized to extrasynaptic sites and later internalized by sAPPα-driven expression of the activity-regulated cytoskeletal-associated protein, Arc. Interestingly, longer exposure to sAPPα increased synaptic levels of GluA1/2 AMPARs. Moreover, the sAPPα-mediated enhancement of LTP in area CA1 of acute hippocampal slices was dependent on CP-AMPARs. Together, these findings show that sAPPα engages mechanisms which specifically enhance the synthesis and cell-surface expression of GluA1 homomers, underpinning the sAPPα-driven enhancement of synaptic plasticity in the hippocampus.
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Affiliation(s)
- Rhys W Livingstone
- Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Megan K Elder
- Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Anurag Singh
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Courteney M Westlake
- Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Warren P Tate
- Department of Biochemistry, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Wickliffe C Abraham
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Joanna M Williams
- Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
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9
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RAGE signaling is required for AMPA receptor dysfunction in the hippocampus of hyperglycemic mice. Physiol Behav 2020; 229:113255. [PMID: 33221393 DOI: 10.1016/j.physbeh.2020.113255] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 10/31/2020] [Accepted: 11/18/2020] [Indexed: 01/08/2023]
Abstract
Diabetes in humans has been associated for a long time with cognitive dysfunction. In rodent animal models, cognitive dysfunction can manifest as impaired hippocampal synaptic plasticity. Particular attention has been concentrated on the receptor for advanced glycation end products (RAGE), which is implicated in multiple diabetic complications involving the development of vascular and peripheral nerve abnormalities. In this study, we hypothesize that RAGE signaling alters glutamate receptor function and expression, impairing synaptic transmission in the hippocampus. Using preparations of hippocampal slices from male mice, we show a RAGE-dependent decrease in long-term potentiation (LTP) and an increase in paired-pulse facilitation (PPF) following streptozotocin (STZ)-induced diabetes. Consistently, in hippocampal cultures from male and female neonatal mice, high glucose caused a RAGE-dependent reduction of AMPA- but not NMDA-evoked currents, and an increase in cytosolic reactive oxygen species (ROS). Consistently, when cultures were co-treated with high glucose and the RAGE antagonist FPS-ZM1, AMPA-evoked currents were unchanged. Hippocampi from STZ-induced hyperglycemic wild type (WT) mice showed increased RAGE expression concomitant with a decrease of both expression and phosphorylation (Ser 831 and 845) of the AMPA GluA1 subunit. We found these changes correlated to activation of the MAPK pathway, consistent with decreased pJNK/JNK ratio and the JNK kinase, pMEK7. As no changes in expression or phosphorylation of regulatory proteins were observed in hippocampi from STZ-induced hyperglycemic RAGE-KO mice, we report a RAGE-dependent impairment in the hippocampi of hyperglycemic WT mice, with reduced AMPA receptor expression/function and LTP deficits.
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10
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Zhu PK, Zheng WS, Zhang P, Jing M, Borden PM, Ali F, Guo K, Feng J, Marvin JS, Wang Y, Wan J, Gan L, Kwan AC, Lin L, Looger LL, Li Y, Zhang Y. Nanoscopic Visualization of Restricted Nonvolume Cholinergic and Monoaminergic Transmission with Genetically Encoded Sensors. NANO LETTERS 2020; 20:4073-4083. [PMID: 32396366 PMCID: PMC7519949 DOI: 10.1021/acs.nanolett.9b04877] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
How neuromodulatory transmitters diffuse into the extracellular space remains an unsolved fundamental biological question, despite wide acceptance of the volume transmission model. Here, we report development of a method combining genetically encoded fluorescent sensors with high-resolution imaging and analysis algorithms which permits the first direct visualization of neuromodulatory transmitter diffusion at various neuronal and non-neuronal cells. Our analysis reveals that acetylcholine and monoamines diffuse at individual release sites with a spread length constant of ∼0.75 μm. These transmitters employ varied numbers of release sites, and when spatially close-packed release sites coactivate they can spillover into larger subcellular areas. Our data indicate spatially restricted (i.e., nonvolume) neuromodulatory transmission to be a prominent intercellular communication mode, reshaping current thinking of control and precision of neuromodulation crucial for understanding behaviors and diseases.
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Affiliation(s)
- Paula K. Zhu
- State Key Laboratory of Membrane Biology and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- Math, Engineering & Science Academy Class of 2020, Albemarle High School, Charlottesville, VA 22901
- Summer Secondary School Neurobiology Class of 2019, Harvard University, Cambridge, MA 02138
- Current address: Undergraduate Class of 2024, Harvard College, Cambridge, MA 02138
| | - W. Sharon Zheng
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908
- Department of Biomedical Engineering Class of 2021, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Peng Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Miao Jing
- State Key Laboratory of Membrane Biology and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- Chinese Institute for Brain Research, Beijing 100871, China
| | - Philip M. Borden
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147
- Current address: LifeEDIT, Research Triangle Park, NC 27709
| | - Farhan Ali
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06511
| | - Kaiming Guo
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Jiesi Feng
- State Key Laboratory of Membrane Biology and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Jonathan S. Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147
| | - Yali Wang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Jinxia Wan
- State Key Laboratory of Membrane Biology and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Li Gan
- Helen and Robert Appel Alzheimer’s Disease Research Institute, Weill Cornell Medicine College, New York, NY 10065
| | - Alex C. Kwan
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06511
| | - Li Lin
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Loren L. Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147
| | - Yulong Li
- State Key Laboratory of Membrane Biology and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Yajun Zhang
- State Key Laboratory of Membrane Biology and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908
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11
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Purkey AM, Dell’Acqua ML. Phosphorylation-Dependent Regulation of Ca 2+-Permeable AMPA Receptors During Hippocampal Synaptic Plasticity. Front Synaptic Neurosci 2020; 12:8. [PMID: 32292336 PMCID: PMC7119613 DOI: 10.3389/fnsyn.2020.00008] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 02/18/2020] [Indexed: 01/28/2023] Open
Abstract
Experience-dependent learning and memory require multiple forms of plasticity at hippocampal and cortical synapses that are regulated by N-methyl-D-aspartate receptors (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type ionotropic glutamate receptors (NMDAR, AMPAR). These plasticity mechanisms include long-term potentiation (LTP) and depression (LTD), which are Hebbian input-specific mechanisms that rapidly increase or decrease AMPAR synaptic strength at specific inputs, and homeostatic plasticity that globally scales-up or -down AMPAR synaptic strength across many or even all inputs. Frequently, these changes in synaptic strength are also accompanied by a change in the subunit composition of AMPARs at the synapse due to the trafficking to and from the synapse of receptors lacking GluA2 subunits. These GluA2-lacking receptors are most often GluA1 homomeric receptors that exhibit higher single-channel conductance and are Ca2+-permeable (CP-AMPAR). This review article will focus on the role of protein phosphorylation in regulation of GluA1 CP-AMPAR recruitment and removal from hippocampal synapses during synaptic plasticity with an emphasis on the crucial role of local signaling by the cAMP-dependent protein kinase (PKA) and the Ca2+calmodulin-dependent protein phosphatase 2B/calcineurin (CaN) that is coordinated by the postsynaptic scaffold protein A-kinase anchoring protein 79/150 (AKAP79/150).
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Affiliation(s)
| | - Mark L. Dell’Acqua
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO, United States
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12
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SYNPLA, a method to identify synapses displaying plasticity after learning. Proc Natl Acad Sci U S A 2020; 117:3214-3219. [PMID: 31974314 DOI: 10.1073/pnas.1919911117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Which neural circuits undergo synaptic changes when an animal learns? Although it is widely accepted that changes in synaptic strength underlie many forms of learning and memory, it remains challenging to connect changes in synaptic strength at specific neural pathways to specific behaviors and memories. Here we introduce SYNPLA (synaptic proximity ligation assay), a synapse-specific, high-throughput, and potentially brain-wide method capable of detecting circuit-specific learning-induced synaptic plasticity.
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13
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Helfer P, Shultz TR. A computational model of systems memory consolidation and reconsolidation. Hippocampus 2019; 30:659-677. [PMID: 31872960 DOI: 10.1002/hipo.23187] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 10/05/2019] [Accepted: 12/04/2019] [Indexed: 12/27/2022]
Abstract
In the mammalian brain, newly acquired memories depend on the hippocampus (HPC) for maintenance and recall, but over time, the neocortex takes over these functions, rendering memories HPC-independent. The process responsible for this transformation is called systems memory consolidation. Reactivation of a well-consolidated memory can trigger a temporary return to a HPC-dependent state, a phenomenon known as systems memory reconsolidation. The neural mechanisms underlying systems memory consolidation and reconsolidation are not well understood. Here, we propose a neural model based on well-documented mechanisms of synaptic plasticity and stability and describe a computational implementation that demonstrates the model's ability to account for a range of findings from the systems consolidation and reconsolidation literature. We derive several predictions from the computational model and suggest experiments that may test its validity.
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Affiliation(s)
- Peter Helfer
- Department of Psychology, McGill University, 2001 McGill College, Montreal, QC, Canada
| | - Thomas R Shultz
- Department of Psychology, McGill University, 2001 McGill College, Montreal, QC, Canada
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14
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Joksimovic SM, Osuru HP, Oklopcic A, Beenhakker MP, Jevtovic-Todorovic V, Todorovic SM. Histone Deacetylase Inhibitor Entinostat (MS-275) Restores Anesthesia-induced Alteration of Inhibitory Synaptic Transmission in the Developing Rat Hippocampus. Mol Neurobiol 2019; 55:222-228. [PMID: 28840475 DOI: 10.1007/s12035-017-0735-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Recent evidence strongly supports the idea that common general anesthetics (GAs) such as isoflurane (Iso) and nitrous oxide (N2O; laughing gas), as well as sedative drugs such as midazolam are neurotoxic for the developing mammalian brain having deleterious effects on neural circuits involved in cognition, learning and memory. However, to date, very little is known about epigenetic mechanisms involved in GA-induced plasticity of synaptic transmission in the hippocampus, the main memory-processing region in the brain. Here, we used patch-clamp recordings of miniature inhibitory post-synaptic currents (mIPSCs) from hippocampal neurons in slice cultures exposed to the clinically relevant GA combination. We found that in vitro exposure to a combination of midazolam, 0.75% Iso, and 70% N2O for 6 h leads to lasting increase in frequency of mIPSCs, while amplitudes and kinetics of the events were spared. Importantly, co-application of entinostat (MS-275), a selective inhibitor of class I histone deacetylases (HDAC), completely reversed GA-induced synaptic plasticity. Furthermore, when given in vivo to P7 pups exposed to GA with midazolam, Iso and N2O for 6 h, MS-275 reversed GA-induced histone-3 hypoacetylation as shown by an increase in Ac-H3 protein expression in the hippocampus. We conclude that exposure to a combination of Iso with N2O and midazolam causes plasticity of mIPSCs in hippocampal neurons by epigenetic mechanisms that target presynaptic sites. We hypothesize that GA-induced epigenetic alterations in inhibitory synaptic transmission in the hippocampus may contribute to altered neuronal excitability and consequently abnormal learning and memory later in life.
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Affiliation(s)
- Srdjan M Joksimovic
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Hari Prasad Osuru
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Azra Oklopcic
- Clinical Trial Office, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Mark P Beenhakker
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Slobodan M Todorovic
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA. .,Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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15
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Rogers EJ, Jada R, Schragenheim-Rozales K, Sah M, Cortes M, Florence M, Levy NS, Moss R, Walikonis RS, Palty R, Shalgi R, Lichtman D, Kavushansky A, Gerges NZ, Kahn I, Umanah GKE, Levy AP. An IQSEC2 Mutation Associated With Intellectual Disability and Autism Results in Decreased Surface AMPA Receptors. Front Mol Neurosci 2019; 12:43. [PMID: 30842726 PMCID: PMC6391579 DOI: 10.3389/fnmol.2019.00043] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 02/01/2019] [Indexed: 12/30/2022] Open
Abstract
We have recently described an A350V mutation in IQSEC2 associated with intellectual disability, autism and epilepsy. We sought to understand the molecular pathophysiology of this mutation with the goal of developing targets for drug intervention. We demonstrate here that the A350V mutation results in interference with the binding of apocalmodulin to the IQ domain of IQSEC2. We further demonstrate that this mutation results in constitutive activation of the guanine nucleotide exchange factor (GEF) activity of IQSEC2 resulting in increased production of the active form of Arf6. In a CRISPR generated mouse model of the A350V IQSEC2 mutation, we demonstrate that the surface expression of GluA2 AMPA receptors in mouse hippocampal tissue was significantly reduced in A350V IQSEC2 mutant mice compared to wild type IQSEC2 mice and that there is a significant reduction in basal synaptic transmission in the hippocampus of A350V IQSEC2 mice compared to wild type IQSEC2 mice. Finally, the A350V IQSEC2 mice demonstrated increased activity, abnormal social behavior and learning as compared to wild type IQSEC2 mice. These findings suggest a model of how the A350V mutation in IQSEC2 may mediate disease with implications for targets for drug therapy. These studies provide a paradigm for a personalized approach to precision therapy for a disease that heretofore has no therapy.
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Affiliation(s)
- Eli J Rogers
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Reem Jada
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | | | - Megha Sah
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Marisol Cortes
- Department of Neurology, Johns Hopkins University, Baltimore, MD, United States
| | - Matthew Florence
- Department of Biopharmaceutical Sciences and Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Nina S Levy
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Rachel Moss
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Randall S Walikonis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Raz Palty
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Reut Shalgi
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Daniela Lichtman
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Alexandra Kavushansky
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Nashaat Z Gerges
- Department of Biopharmaceutical Sciences and Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Itamar Kahn
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - George K E Umanah
- Department of Neurology, Johns Hopkins University, Baltimore, MD, United States
| | - Andrew P Levy
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
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16
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Medin T, Jensen V, Skare Ø, Storm-Mathisen J, Hvalby Ø, Bergersen LH. Altered α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor function and expression in hippocampus in a rat model of attention-deficit/hyperactivity disorder (ADHD). Behav Brain Res 2018; 360:209-215. [PMID: 30552946 DOI: 10.1016/j.bbr.2018.12.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/28/2018] [Accepted: 12/11/2018] [Indexed: 12/22/2022]
Abstract
Glutamatergic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) carry the bulk of excitatory synaptic transmission. Their modulation plays key roles in synaptic plasticity, which underlies hippocampal learning and memory. A dysfunctional glutamatergic system may negatively affect learning abilities and underlie symptoms of attention-deficit/hyperactivity disorder (ADHD). The aim of this study was to investigate whether the expression and function of AMPARs were altered in ADHD. We recorded AMPAR mediated synaptic transmission at hippocampal excitatory synapses and quantified immunogold labelling density of AMPAR subunits GluA1 and GluA2/3 in a rat model for ADHD; the spontaneously hypertensive rat (SHR). Electrophysiological recordings showed significantly reduced AMPAR mediated synaptic transmission at the CA3-to-CA1 pyramidal cell synapses in stratum radiatum and stratum oriens in SHRs compared to control rats. Electronmicroscopic immunogold quantifications did not show any statistically significant changes in labelling densities of the GluA1 subunit of the AMPAR on dendritic spines in stratum radiatum or in stratum oriens. However, there was a significant increase of the GluA2/3 subunit intracellularly in stratum oriens in SHR compared to control, interpreted as a compensatory effect. The proportion of synapses lacking AMPAR subunit labelling was the same in the two genotypes. In addition, electronmicroscopic examination of tissue morphology showed the density of this type of synapse (i.e., asymmetric synapses on spines), and the average size of the synaptic membranes, to be the same. AMPAR dysfunction, possibly involving molecular changes, in hippocampus may in part reflect altered learning in individuals with ADHD.
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Affiliation(s)
- Tirill Medin
- OsloMet - Oslo Metropolitan University, Faculty of Health Sciences, P.O. Box 4, St. Olavs Plass, 0130, Oslo, Norway; The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316, Oslo, Norway; Synaptic Neurochemistry and Amino Acid Transporters Labs, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences (IMB) and Healthy Brain Ageing Centre (SERTA), University of Oslo, NO-0317, Oslo, Norway.
| | - Vidar Jensen
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences (IMB), University of Oslo, NO-0317, Oslo, Norway
| | - Øyvind Skare
- Department of Occupational Medicine and Epidemiology, National Institute of Occupational Health, Oslo, Norway
| | - Jon Storm-Mathisen
- Synaptic Neurochemistry and Amino Acid Transporters Labs, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences (IMB) and Healthy Brain Ageing Centre (SERTA), University of Oslo, NO-0317, Oslo, Norway
| | - Øyvind Hvalby
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences (IMB), University of Oslo, NO-0317, Oslo, Norway
| | - Linda Hildegard Bergersen
- The Brain and Muscle Energy Group, Electron Microscopy Laboratory, Department of Oral Biology, University of Oslo, NO-0316, Oslo, Norway; Synaptic Neurochemistry and Amino Acid Transporters Labs, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences (IMB) and Healthy Brain Ageing Centre (SERTA), University of Oslo, NO-0317, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, DK-2200, Copenhagen N, Denmark
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17
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Phosphorylation of synaptic GTPase-activating protein (synGAP) by polo-like kinase (Plk2) alters the ratio of its GAP activity toward HRas, Rap1 and Rap2 GTPases. Biochem Biophys Res Commun 2018; 503:1599-1604. [PMID: 30049443 DOI: 10.1016/j.bbrc.2018.07.087] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 07/18/2018] [Indexed: 11/20/2022]
Abstract
SynGAP is a Ras and Rap GTPase-activating protein (GAP) found in high concentration in the postsynaptic density (PSD) fraction from mammalian forebrain where it binds to PDZ domains of PSD-95. Phosphorylation of pure recombinant synGAP by Ca2+/calmodulin-dependent protein kinase II (CaMKII) shifts the balance of synGAP's GAP activity toward inactivation of Rap1; whereas phosphorylation by cyclin-dependent kinase 5 (CDK5) has the opposite effect, shifting the balance toward inactivation of HRas. These shifts in balance contribute to regulation of the numbers of surface AMPA receptors, which rise during synaptic potentiation (CaMKII) and fall during synaptic scaling (CDK5). Polo-like kinase 2 (Plk2/SNK), like CDK5, contributes to synaptic scaling. These two kinases act in concert to reduce the number of surface AMPA receptors following elevated neuronal activity by tagging spine-associated RapGAP protein (SPAR) for degradation, thus raising the level of activated Rap. Here we show that Plk2 also phosphorylates and regulates synGAP. Phosphorylation of synGAP by Plk2 stimulates its GAP activity toward HRas by 65%, and toward Rap1 by 16%. Simultaneous phosphorylation of synGAP by Plk2 and CDK5 at distinct sites produces an additive increase in GAP activity toward HRas (∼230%) and a smaller, non-additive increase in activity toward Rap1 (∼15%). Dual phosphorylation also produces an increase in GAP activity toward Rap2 (∼40-50%), an effect not produced by either kinase alone. As we previously observed for CDK5, addition of Ca2+/CaM causes a substrate-directed doubling of the rate and stoichiometry of phosphorylation of synGAP by Plk2, targeting residues also phosphorylated by CaMKII. In summary, phosphorylation by Plk2, like CDK5, shifts the ratio of GAP activity of synGAP to produce a greater decrease in active Ras than in active Rap, which would produce a shift toward a decrease in the number of surface AMPA receptors in neuronal dendrites.
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18
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Zhang L, Zhang P, Wang G, Zhang H, Zhang Y, Yu Y, Zhang M, Xiao J, Crespo P, Hell JW, Lin L, Huganir RL, Zhu JJ. Ras and Rap Signal Bidirectional Synaptic Plasticity via Distinct Subcellular Microdomains. Neuron 2018; 98:783-800.e4. [PMID: 29706584 PMCID: PMC6192044 DOI: 10.1016/j.neuron.2018.03.049] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 02/12/2018] [Accepted: 03/27/2018] [Indexed: 11/16/2022]
Abstract
How signaling molecules achieve signal diversity and specificity is a long-standing cell biology question. Here we report the development of a targeted delivery method that permits specific expression of homologous Ras-family small GTPases (i.e., Ras, Rap2, and Rap1) in different subcellular microdomains, including the endoplasmic reticulum, lipid rafts, bulk membrane, lysosomes, and Golgi complex, in rodent hippocampal CA1 neurons. The microdomain-targeted delivery, combined with multicolor fluorescence protein tagging and high-resolution dual-quintuple simultaneous patch-clamp recordings, allows systematic analysis of microdomain-specific signaling. The analysis shows that Ras signals long-term potentiation via endoplasmic reticulum PI3K and lipid raft ERK, whereas Rap2 and Rap1 signal depotentiation and long-term depression via bulk membrane JNK and lysosome p38MAPK, respectively. These results establish an effective subcellular microdomain-specific targeted delivery method and unveil subcellular microdomain-specific signaling as the mechanism for homologous Ras and Rap to achieve signal diversity and specificity to control multiple forms of synaptic plasticity.
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Affiliation(s)
- Lei Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Peng Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Guangfu Wang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Center for Life Sciences, School of Life Science and Technology, Harbin Institute of Technology, Harbin 150001, China
| | - Huaye Zhang
- Department of Microbiology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | - Yajun Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Yilin Yu
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Mingxu Zhang
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242, USA; Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Jian Xiao
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Piero Crespo
- Instituto de Biomedicina y Biotecnología de Cantabriaand CIBERONC, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Cantabria, Santander 39011, Spain
| | - Johannes W Hell
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242, USA; Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Li Lin
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China.
| | - Richard L Huganir
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - J Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China; School of Medicine, Ningbo University, Ningbo 315010, China; Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen, 6525 EN, Nijmegen, the Netherlands
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19
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Enhanced AMPA Receptor Trafficking Mediates the Anorexigenic Effect of Endogenous Glucagon-like Peptide-1 in the Paraventricular Hypothalamus. Neuron 2017; 96:897-909.e5. [PMID: 29056294 DOI: 10.1016/j.neuron.2017.09.042] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 08/16/2017] [Accepted: 09/22/2017] [Indexed: 12/27/2022]
Abstract
Glucagon-like Peptide 1 (GLP-1)-expressing neurons in the hindbrain send robust projections to the paraventricular nucleus of the hypothalamus (PVN), which is involved in the regulation of food intake. Here, we describe that stimulation of GLP-1 afferent fibers within the PVN is sufficient to suppress food intake independent of glutamate release. We also show that GLP-1 receptor (GLP-1R) activation augments excitatory synaptic strength in PVN corticotropin-releasing hormone (CRH) neurons, with GLP-1R activation promoting a protein kinase A (PKA)-dependent signaling cascade leading to phosphorylation of serine S845 on GluA1 AMPA receptors and their trafficking to the plasma membrane. Finally, we show that postnatal depletion of GLP-1R in the PVN increases food intake and causes obesity. This study provides a comprehensive multi-level (circuit, synaptic, and molecular) explanation of how food intake behavior and body weight are regulated by endogenous central GLP-1. VIDEO ABSTRACT.
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20
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Lim CS, Wen C, Sheng Y, Wang G, Zhou Z, Wang S, Zhang H, Ye A, Zhu JJ. Piconewton-Scale Analysis of Ras-BRaf Signal Transduction with Single-Molecule Force Spectroscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2017; 13:10.1002/smll.201701972. [PMID: 28809097 PMCID: PMC6272124 DOI: 10.1002/smll.201701972] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/10/2017] [Indexed: 06/07/2023]
Abstract
Intermolecular interactions dominate the behavior of signal transduction in various physiological and pathological cell processes, yet assessing these interactions remains a challenging task. Here, this study reports a single-molecule force spectroscopic method that enables functional delineation of two interaction sites (≈35 pN and ≈90 pN) between signaling effectors Ras and BRaf in the canonical mitogen-activated protein kinase (MAPK) pathway. This analysis reveals mutations on BRaf at Q257 and A246, two sites frequently linked to cardio-faciocutaneous syndrome, result in ≈10-30 pN alterations in RasBRaf intermolecular binding force. The magnitude of changes in RasBRaf binding force correlates with the size of alterations in protein affinity and in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-sensitive glutamate receptor (-R)-mediated synaptic transmission in neurons expressing replacement BRaf mutants, and predicts the extent of learning impairments in animals expressing replacement BRaf mutants. These results establish single-molecule force spectroscopy as an effective platform for evaluating the piconewton-level interaction of signaling molecules and predicting the behavior outcome of signal transduction.
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Affiliation(s)
- Chae-Seok Lim
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Cheng Wen
- School of Electronic Engineering and Computer Science, Peking University, Beijing, 100871, China
| | - Yanghui Sheng
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Undergraduate Class of 2011, Yuanpei Honors College, Peking University, Beijing, 100871, China
- Institute of Molecular Medicine, Peking University, Beijing, 100871, China
- School of Life Sciences, Peking University, Beijing, 100871, China
| | - Guangfu Wang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Zhuan Zhou
- Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Shiqiang Wang
- School of Life Sciences, Peking University, Beijing, 100871, China
| | - Huaye Zhang
- Department of Microbiology and Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Anpei Ye
- School of Electronic Engineering and Computer Science, Peking University, Beijing, 100871, China
| | - J Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Institute of Neuroscience, Zhejiang University School of Medicine, Hangzhou, 310058, China
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, 6525, EN, Nijmegen, Netherlands
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21
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Renner MC, Albers EH, Gutierrez-Castellanos N, Reinders NR, van Huijstee AN, Xiong H, Lodder TR, Kessels HW. Synaptic plasticity through activation of GluA3-containing AMPA-receptors. eLife 2017; 6:25462. [PMID: 28762944 PMCID: PMC5578739 DOI: 10.7554/elife.25462] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 07/31/2017] [Indexed: 11/13/2022] Open
Abstract
Excitatory synaptic transmission is mediated by AMPA-type glutamate receptors (AMPARs). In CA1 pyramidal neurons of the hippocampus two types of AMPARs predominate: those that contain subunits GluA1 and GluA2 (GluA1/2), and those that contain GluA2 and GluA3 (GluA2/3). Whereas subunits GluA1 and GluA2 have been extensively studied, the contribution of GluA3 to synapse physiology has remained unclear. Here we show in mice that GluA2/3s are in a low-conductance state under basal conditions, and although present at synapses they contribute little to synaptic currents. When intracellular cyclic AMP (cAMP) levels rise, GluA2/3 channels shift to a high-conductance state, leading to synaptic potentiation. This cAMP-driven synaptic potentiation requires the activation of both protein kinase A (PKA) and the GTPase Ras, and is induced upon the activation of β-adrenergic receptors. Together, these experiments reveal a novel type of plasticity at CA1 hippocampal synapses that is expressed by the activation of GluA3-containing AMPARs.
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Affiliation(s)
- Maria C Renner
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Eva Hh Albers
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Nicolas Gutierrez-Castellanos
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Niels R Reinders
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Aile N van Huijstee
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Hui Xiong
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Tessa R Lodder
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Helmut W Kessels
- Synaptic Plasticity and Behavior Group, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
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22
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General Anesthesia Causes Epigenetic Histone Modulation of c-Fos and Brain-derived Neurotrophic Factor, Target Genes Important for Neuronal Development in the Immature Rat Hippocampus. Anesthesiology 2017; 124:1311-1327. [PMID: 27028464 DOI: 10.1097/aln.0000000000001111] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Early postnatal exposure to general anesthesia (GA) may be detrimental to brain development, resulting in long-term cognitive impairments. Older literature suggests that in utero exposure of rodents to GA causes cognitive impairments in the first-generation as well as in the second-generation offspring never exposed to GA. Thus, the authors hypothesize that transient exposure to GA during critical stages of synaptogenesis causes epigenetic changes in chromatin with deleterious effects on transcription of target genes crucial for proper synapse formation and cognitive development. They focus on the effects of GA on histone acetyltransferase activity of cAMP-responsive element-binding protein and the histone-3 acetylation status in the promoters of the target genes brain-derived neurotrophic factor and cellular Finkel-Biskis-Jinkins murine sarcoma virus osteosarcoma oncogene (c-Fos) known to regulate the development of neuronal morphology and function. METHODS Seven-day-old rat pups were exposed to a sedative dose of midazolam followed by combined nitrous oxide and isoflurane anesthesia for 6 h. Hippocampal neurons and organotypic hippocampal slices were cultured in vitro and exposed to GA for 24 h. RESULTS GA caused epigenetic modulations manifested as histone-3 hypoacetylation (decrease of 25 to 30%, n = 7 to 9) and fragmentation of cAMP-responsive element-binding protein (two-fold increase, n = 6) with 25% decrease in its histone acetyltransferase activity, which resulted in down-regulated transcription of brain-derived neurotrophic factor (0.2- to 0.4-fold, n = 7 to 8) and cellular Finkel-Biskis-Jinkins murine sarcoma virus osteosarcoma oncogene (about 0.2-fold, n = 10 to 12). Reversal of histone hypoacetylation with sodium butyrate blocked GA-induced morphological and functional impairments of neuronal development and synaptic communication. CONCLUSION Long-term impairments of neuronal development and synaptic communication could be caused by GA-induced epigenetic phenomena.
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Lim CS, Kang X, Mirabella V, Zhang H, Bu Q, Araki Y, Hoang ET, Wang S, Shen Y, Choi S, Kaang BK, Chang Q, Pang ZP, Huganir RL, Zhu JJ. BRaf signaling principles unveiled by large-scale human mutation analysis with a rapid lentivirus-based gene replacement method. Genes Dev 2017; 31:537-552. [PMID: 28404629 PMCID: PMC5393050 DOI: 10.1101/gad.294413.116] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 03/13/2017] [Indexed: 12/18/2022]
Abstract
Rapid advances in genetics are linking mutations on genes to diseases at an exponential rate, yet characterizing the gene-mutation-cell-behavior relationships essential for precision medicine remains a daunting task. More than 350 mutations on small GTPase BRaf are associated with various tumors, and ∼40 mutations are associated with the neurodevelopmental disorder cardio-facio-cutaneous syndrome (CFC). We developed a fast cost-effective lentivirus-based rapid gene replacement method to interrogate the physiopathology of BRaf and ∼50 disease-linked BRaf mutants, including all CFC-linked mutants. Analysis of simultaneous multiple patch-clamp recordings from 6068 pairs of rat neurons with validation in additional mouse and human neurons and multiple learning tests from 1486 rats identified BRaf as the key missing signaling effector in the common synaptic NMDA-R-CaMKII-SynGap-Ras-BRaf-MEK-ERK transduction cascade. Moreover, the analysis creates the original big data unveiling three general features of BRaf signaling. This study establishes the first efficient procedure that permits large-scale functional analysis of human disease-linked mutations essential for precision medicine.
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Affiliation(s)
- Chae-Seok Lim
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.,Department of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Xi Kang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Vincent Mirabella
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.,Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
| | - Huaye Zhang
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.,Department of Microbiology, Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
| | - Qian Bu
- Waisman Center, University of Wisconsin School of Medicine, Madison, Wisconsin 53705, USA.,Department of Medical Genetics, University of Wisconsin School of Medicine, Madison, Wisconsin 53705, USA
| | - Yoichi Araki
- Department of Neuroscience, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - Elizabeth T Hoang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.,Undergraduate Class of 2014, Department of Psychology, University of Virginia College of Arts and Sciences, Charlottesville, Virginia 22908, USA
| | - Shiqiang Wang
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing 100871, China
| | - Ying Shen
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Sukwoo Choi
- Department of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Bong-Kiun Kaang
- Department of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Qiang Chang
- Waisman Center, University of Wisconsin School of Medicine, Madison, Wisconsin 53705, USA.,Department of Medical Genetics, University of Wisconsin School of Medicine, Madison, Wisconsin 53705, USA
| | - Zhiping P Pang
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.,Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
| | - Richard L Huganir
- Department of Neuroscience, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
| | - J Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.,Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
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24
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Yan X, Zhang B, Lu W, Peng L, Yang Q, Cao W, Lin S, Yu W, Li X, Ke Y, Li S, Yang W, Luo J. Increased Src Family Kinase Activity Disrupts Excitatory Synaptic Transmission and Impairs Remote Fear Memory in Forebrain Shp2-Deficient Mice. Mol Neurobiol 2016; 54:7235-7250. [PMID: 27796759 DOI: 10.1007/s12035-016-0222-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 10/13/2016] [Indexed: 11/29/2022]
Abstract
Src homolog domain-containing phosphatase 2 (Shp2) signals a variety of cellular and physiological functions including learning and memory. Dysregulation of ERK signaling is known to be responsible for the cognitive deficits associated with gain-of-function mutated Shp2 mimicking Noonan syndrome. However, here, we report that CaMKIIα-cre induced knockout (CaSKO) of Shp2 in hippocampal pyramidal neurons resulted in increased Src activity, upregulated phosphorylation of N-methyl-D-aspartate receptors (NMDARs) at Y1325 of GluN2A and at Y1472 of GluN2B, disrupted the balance of synaptic transmission, and impaired long-term potentiation and remote contextual fear memory. Administration of PP2, a specific Src family kinase inhibitor, reversed the tyrosine phosphorylation of NMDARs, restored basal synaptic transmission, and rescued the contextual fear memory deficit in CaSKO mice without altering the phospho-ERK level. Taken together, our results reveal a novel role of Shp2 in NMDAR-dependent synaptic function and fear memory via the Src signaling pathway rather than the ERK pathway, and suggest a complicated mechanism for Shp2-associated cognitive deficits.
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Affiliation(s)
- Xunyi Yan
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Bin Zhang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Wen Lu
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Lin Peng
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Qian Yang
- BIO-X Institute, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Wei Cao
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Shen Lin
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Wenyue Yu
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Xiaoming Li
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Yuehai Ke
- Department of Pathology, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Shengtian Li
- BIO-X Institute, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Wei Yang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
| | - Jianhong Luo
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
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Sheng Y, Zhang L, Su SC, Tsai LH, Julius Zhu J. Cdk5 is a New Rapid Synaptic Homeostasis Regulator Capable of Initiating the Early Alzheimer-Like Pathology. Cereb Cortex 2016; 26:2937-51. [PMID: 26088971 PMCID: PMC4898661 DOI: 10.1093/cercor/bhv032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cyclin-dependent kinase 5 (Cdk5) is a serine/threonine kinase implicated in synaptic plasticity, behavior, and cognition, yet its synaptic function remains poorly understood. Here, we report that physiological Cdk5 signaling in rat hippocampal CA1 neurons regulates homeostatic synaptic transmission using an unexpectedly rapid mechanism that is different from all known slow homeostatic regulators, such as beta amyloid (Aβ) and activity-regulated cytoskeleton-associated protein (Arc, aka Arg3.1). Interestingly, overproduction of the potent Cdk5 activator p25 reduces synapse density, and dynamically regulates synaptic size by suppressing or enhancing Aβ/Arc production. Moreover, chronic overproduction of p25, seen in Alzheimer's patients, induces initially concurrent reduction in synapse density and increase in synaptic size characteristic of the early Alzheimer-like pathology, and later persistent synapse elimination in intact brains. These results identify Cdk5 as the regulator of a novel rapid form of homeostasis at central synapses and p25 as the first molecule capable of initiating the early Alzheimer's synaptic pathology.
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Affiliation(s)
- Yanghui Sheng
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Undergraduate Class of 2011, Yuanpei Honors College, Peking University, Beijing100871, China
- Current address: Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Lei Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Susan C. Su
- Picower Institute for Learning and Memory and Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Li-Huei Tsai
- Picower Institute for Learning and Memory and Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - J. Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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26
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Brown JC, Petersen A, Zhong L, Himelright ML, Murphy JA, Walikonis RS, Gerges NZ. Bidirectional regulation of synaptic transmission by BRAG1/IQSEC2 and its requirement in long-term depression. Nat Commun 2016; 7:11080. [PMID: 27009485 PMCID: PMC4820844 DOI: 10.1038/ncomms11080] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 02/16/2016] [Indexed: 01/09/2023] Open
Abstract
Dysfunction of the proteins regulating synaptic function can cause synaptic plasticity imbalance that underlies neurological disorders such as intellectual disability. A study found that four distinct mutations within BRAG1, an Arf-GEF synaptic protein, each led to X-chromosome-linked intellectual disability (XLID). Although the physiological functions of BRAG1 are poorly understood, each of these mutations reduces BRAG1's Arf-GEF activity. Here we show that BRAG1 is required for the activity-dependent removal of AMPA receptors in rat hippocampal pyramidal neurons. Moreover, we show that BRAG1 bidirectionally regulates synaptic transmission. On one hand, BRAG1 is required for the maintenance of synaptic transmission. On the other hand, BRAG1 expression enhances synaptic transmission, independently of BRAG1 Arf-GEF activity or neuronal activity, but dependently on its C-terminus interactions. This study demonstrates a dual role of BRAG1 in synaptic function and highlights the functional relevance of reduced BRAG1 Arf-GEF activity as seen in the XLID-associated human mutations.
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Affiliation(s)
- Joshua C Brown
- Department of Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin 53132 USA
| | - Amber Petersen
- Department of Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin 53132 USA
| | - Ling Zhong
- Department of Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin 53132 USA
| | - Miranda L Himelright
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269 USA
| | - Jessica A Murphy
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269 USA
| | - Randall S Walikonis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269 USA
| | - Nashaat Z Gerges
- Department of Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin 53132 USA
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27
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Sweatt JD. Dynamic DNA methylation controls glutamate receptor trafficking and synaptic scaling. J Neurochem 2016; 137:312-30. [PMID: 26849493 DOI: 10.1111/jnc.13564] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 01/27/2016] [Accepted: 01/30/2016] [Indexed: 12/27/2022]
Abstract
Hebbian plasticity, including long-term potentiation and long-term depression, has long been regarded as important for local circuit refinement in the context of memory formation and stabilization. However, circuit development and stabilization additionally relies on non-Hebbian, homeostatic, forms of plasticity such as synaptic scaling. Synaptic scaling is induced by chronic increases or decreases in neuronal activity. Synaptic scaling is associated with cell-wide adjustments in postsynaptic receptor density, and can occur in a multiplicative manner resulting in preservation of relative synaptic strengths across the entire neuron's population of synapses. Both active DNA methylation and demethylation have been validated as crucial regulators of gene transcription during learning, and synaptic scaling is known to be transcriptionally dependent. However, it has been unclear whether homeostatic forms of plasticity such as synaptic scaling are regulated via epigenetic mechanisms. This review describes exciting recent work that has demonstrated a role for active changes in neuronal DNA methylation and demethylation as a controller of synaptic scaling and glutamate receptor trafficking. These findings bring together three major categories of memory-associated mechanisms that were previously largely considered separately: DNA methylation, homeostatic plasticity, and glutamate receptor trafficking. This review describes exciting recent work that has demonstrated a role for active changes in neuronal DNA methylation and demethylation as a controller of synaptic scaling and glutamate receptor trafficking. These findings bring together three major categories of memory-associated mechanisms that were previously considered separately: glutamate receptor trafficking, DNA methylation, and homeostatic plasticity.
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Affiliation(s)
- J David Sweatt
- Department of Neurobiology, Evelyn F. McKnight Brain Institute, Civitan International Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA
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28
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Synaptically Localized Mitogen-Activated Protein Kinases: Local Substrates and Regulation. Mol Neurobiol 2015; 53:6309-6315. [PMID: 26567109 DOI: 10.1007/s12035-015-9535-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 11/08/2015] [Indexed: 12/22/2022]
Abstract
Mitogen-activated protein kinases (MAPKs) are expressed in postmitotic neurons and act as important regulators in intracellular signaling. In addition to their nuclear distribution and roles in regulating gene expression, MAPKs, especially the extracellular signal-regulated kinase (ERK) subclass, reside in peripheral dendritic spines and synapses, including the postsynaptic density (PSD) microdomain. This peripheral pool of MAPKs/ERKs is either constitutively active or sensitive to changing synaptic input. Active MAPKs directly interact with and phosphorylate local substrates to alter their trafficking and subcellular/subsynaptic distributions, through which MAPKs regulate function of substrates and contribute to long-lasting synaptic plasticity. A number of physiologically relevant substrates of MAPKs have been identified at synaptic sites. Central among them are key synaptic scaffold proteins (PSD-95 and PSD-93), cadherin-associated proteins (δ-catenin), Kv4.2 K+ channels, and metabotropic glutamate receptors. Through a reversible phosphorylation event, MAPKs rapidly and efficiently modulate the function of these substrates and thus determine the strength of synaptic transmission. This review summarizes the recent progress in cell biology of synaptic MAPKs and analyzes roles of this specific pool of MAPKs in regulating local substrates and synaptic plasticity.
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29
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Wang G, Bochorishvili G, Chen Y, Salvati KA, Zhang P, Dubel SJ, Perez-Reyes E, Snutch TP, Stornetta RL, Deisseroth K, Erisir A, Todorovic SM, Luo JH, Kapur J, Beenhakker MP, Zhu JJ. CaV3.2 calcium channels control NMDA receptor-mediated transmission: a new mechanism for absence epilepsy. Genes Dev 2015. [PMID: 26220996 PMCID: PMC4526737 DOI: 10.1101/gad.260869.115] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
CaV3.2 T-type calcium channels, encoded by CACNA1H, are expressed throughout the brain, yet their general function remains unclear. We discovered that CaV3.2 channels control NMDA-sensitive glutamatergic receptor (NMDA-R)-mediated transmission and subsequent NMDA-R-dependent plasticity of AMPA-R-mediated transmission at rat central synapses. Interestingly, functional CaV3.2 channels primarily incorporate into synapses, replace existing CaV3.2 channels, and can induce local calcium influx to control NMDA transmission strength in an activity-dependent manner. Moreover, human childhood absence epilepsy (CAE)-linked hCaV3.2(C456S) mutant channels have a higher channel open probability, induce more calcium influx, and enhance glutamatergic transmission. Remarkably, cortical expression of hCaV3.2(C456S) channels in rats induces 2- to 4-Hz spike and wave discharges and absence-like epilepsy characteristic of CAE patients, which can be suppressed by AMPA-R and NMDA-R antagonists but not T-type calcium channel antagonists. These results reveal an unexpected role of CaV3.2 channels in regulating NMDA-R-mediated transmission and a novel epileptogenic mechanism for human CAE.
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Affiliation(s)
- Guangfu Wang
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Genrieta Bochorishvili
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Yucai Chen
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Kathryn A Salvati
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Peng Zhang
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Steve J Dubel
- Laboratoire de Génomique Fonctionnelle, Département de Physiologie, Unité Propre de Recherche 2580, Centre National de la Recherche Scientifique, 34396 Montpellier, France
| | - Edward Perez-Reyes
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Terrance P Snutch
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Ruth L Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, California 94305, USA; Howard Hughes Medical Institute, Stanford University, Stanford, California 94305, USA
| | - Alev Erisir
- Department of Psychology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Slobodan M Todorovic
- Department of Anesthesiology, University of Virginia, Charlottesville, Virginia 22908, USA; Department of Neuroscience, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Jian-Hong Luo
- Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Mark P Beenhakker
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - J Julius Zhu
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA; Department of Neuroscience, University of Virginia, Charlottesville, Virginia 22908, USA
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30
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Guo W, Polich ED, Su J, Gao Y, Christopher DM, Allan AM, Wang M, Wang F, Wang G, Zhao X. Fragile X Proteins FMRP and FXR2P Control Synaptic GluA1 Expression and Neuronal Maturation via Distinct Mechanisms. Cell Rep 2015; 11:1651-66. [PMID: 26051932 DOI: 10.1016/j.celrep.2015.05.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 02/18/2015] [Accepted: 05/07/2015] [Indexed: 01/01/2023] Open
Abstract
Fragile X mental retardation protein (FMRP) and its autosomal paralog FXR2P are selective neuronal RNA-binding proteins, and mice that lack either protein exhibit cognitive deficits. Although double-mutant mice display more severe learning deficits than single mutants, the molecular mechanism behind this remains unknown. In the present study, we discovered that FXR2P (also known as FXR2) is important for neuronal dendritic development. FMRP and FXR2P additively promote the maturation of new neurons by regulating a common target, the AMPA receptor GluA1, but they do so via distinct mechanisms: FXR2P binds and stabilizes GluA1 mRNA and enhances subsequent protein expression, whereas FMRP promotes GluA1 membrane delivery. Our findings unveil important roles for FXR2P and GluA1 in neuronal development, uncover a regulatory mechanism of GluA1, and reveal a functional convergence between fragile X proteins in neuronal development.
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Affiliation(s)
- Weixiang Guo
- State Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Neuroscience, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA
| | - Eric D Polich
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Neuroscience, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA
| | - Juan Su
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Neuroscience, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA
| | - Yu Gao
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Neuroscience, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA
| | - Devin M Christopher
- Department of Neurosciences, University of New Mexico, Albuquerque, NM 87131, USA
| | - Andrea M Allan
- Department of Neurosciences, University of New Mexico, Albuquerque, NM 87131, USA
| | - Min Wang
- State Key Laboratory for Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Feifei Wang
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Neuroscience, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA
| | - Guangfu Wang
- Department of Pharmacology, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | - Xinyu Zhao
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Neuroscience, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53705, USA.
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31
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Santerre JL, Rogow JA, Kolitz EB, Pal R, Landin JD, Gigante ED, Werner DF. Ethanol dose-dependently elicits opposing regulatory effects on hippocampal AMPA receptor GluA2 subunits through a zeta inhibitory peptide-sensitive kinase in adolescent and adult Sprague-Dawley rats. Neuroscience 2014; 280:50-9. [PMID: 25218807 PMCID: PMC4482479 DOI: 10.1016/j.neuroscience.2014.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 09/02/2014] [Accepted: 09/02/2014] [Indexed: 10/24/2022]
Abstract
AMPA receptor GluA2 subunits are strongly implicated in cognition, and prior work suggests that these subunits may be regulated by atypical protein kinase C (aPKC) isoforms. The present study assessed whether hippocampal and cortical AMPA receptor GluA2 subunit regulation may be an underlying factor in known age-related differences to cognitive-impairing doses of ethanol, and if aPKC isoforms modulate such responses. Hippocampal AMPA receptor GluA2 subunit, protein kinase Mζ (PKMζ), and PKCι/λ expression were elevated during adolescence compared to adults. 1 h following a low-dose (1.0-g/kg) ethanol exposure, hippocampal AMPA receptor GluA2 subunit serine 880 phosphorylation was decreased in adolescents, but was increased in adults. Age-dependent changes in GluA2 subunit phosphorylation were paralleled by alterations in aPKC isoforms, and zeta inhibitory peptide (ZIP) administration prevented ethanol-induced increases in both in adults. Ethanol-induced changes in GluA2 subunit phosphorylation were associated with delayed regulation in synaptosomal GluA2 subunit expression 24 h later. A higher ethanol dose (3.5-g/kg) failed to elicit changes in most measures in the hippocampus at either age. Similar to the hippocampus, analysis of cerebral cortical tissue also revealed age-related declines. However, no demonstrable effects were found following a low-dose ethanol exposure at either age. High-dose ethanol exposure reduced adolescent GluA2 subunit phosphorylation and aPKC isoform expression that were again accompanied by delayed reductions in synaptosomal GluA2 subunit expression. Together, these results suggest that GluA2-containing AMPA receptor modulation by aPKC isoforms is age-, region- and dose-dependently regulated, and may potentially be involved in developmentally regulated ethanol-induced cognitive impairment and other ethanol behaviors.
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Affiliation(s)
- J L Santerre
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, NY 13902, USA
| | - J A Rogow
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, NY 13902, USA
| | - E B Kolitz
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, NY 13902, USA
| | - R Pal
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, NY 13902, USA
| | - J D Landin
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, NY 13902, USA
| | - E D Gigante
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, NY 13902, USA
| | - D F Werner
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, NY 13902, USA.
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Lee KJ, Hoe HS, Pak DT. Plk2 Raps up Ras to subdue synapses. Small GTPases 2014; 2:162-166. [PMID: 21776418 DOI: 10.4161/sgtp.2.3.16454] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 05/11/2011] [Indexed: 11/19/2022] Open
Abstract
We recently identified the activity-inducible protein kinase Plk2 as a novel overseer of the balance between Ras and Rap small GTPases. Plk2 achieves a profound level of regulatory control by interacting with and phosphorylating at least four Ras and Rap guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). Combined, these actions result in synergistic suppression of Ras and hyperstimulation of Rap signaling. Perturbation of Plk2 function abolished homeostatic adaptation of synapses to enhanced activity and impaired behavioral adaptation in various learning tasks, indicating that this regulation was critical for maintaining appropriate Ras/Rap levels. These studies provide insights into the highly cooperative nature of Ras and Rap regulation in neurons. However, different GEF and GAP substrates of Plk2 also controlled specific aspects of dendritic spine morphology, illustrating the ability of individual GAPs/GEFs to assemble microdomains of Ras and Rap signaling that respond to different stimuli and couple to distinct output pathways.
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Affiliation(s)
- Kea Joo Lee
- Department of Pharmacology; Georgetown University; Medical Center; Washington, DC USA
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Lim CS, Hoang ET, Viar KE, Stornetta RL, Scott MM, Zhu JJ. Pharmacological rescue of Ras signaling, GluA1-dependent synaptic plasticity, and learning deficits in a fragile X model. Genes Dev 2014; 28:273-89. [PMID: 24493647 PMCID: PMC3923969 DOI: 10.1101/gad.232470.113] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Fragile X syndrome, caused by the loss of Fmr1 gene function, is the most common form of inherited mental retardation. Lim et al. find that compounds activating serotonin (5HT) subtype 2B receptors or dopamine (DA) subtype 1-like receptors and those inhibiting 5HT2A-Rs or D2-Rs enhance Ras signaling, GluA1-dependent synaptic plasticity, and learning in Fmr1 knockout mice. Combining 5HT and DA compounds at low doses synergistically restored normal learning. This suggests that properly dosed and combined FDA-approved psychoactive drugs may effectively treat the cognitive impairment associated with fragile X syndrome. Fragile X syndrome, caused by the loss of Fmr1 gene function, is the most common form of inherited mental retardation, with no effective treatment. Using a tractable animal model, we investigated mechanisms of action of a few FDA-approved psychoactive drugs that modestly benefit the cognitive performance in fragile X patients. Here we report that compounds activating serotonin (5HT) subtype 2B receptors (5HT2B-Rs) or dopamine (DA) subtype 1-like receptors (D1-Rs) and/or those inhibiting 5HT2A-Rs or D2-Rs moderately enhance Ras–PI3K/PKB signaling input, GluA1-dependent synaptic plasticity, and learning in Fmr1 knockout mice. Unexpectedly, combinations of these 5HT and DA compounds at low doses synergistically stimulate Ras–PI3K/PKB signal transduction and GluA1-dependent synaptic plasticity and remarkably restore normal learning in Fmr1 knockout mice without causing anxiety-related side effects. These findings suggest that properly dosed and combined FDA-approved psychoactive drugs may effectively treat the cognitive impairment associated with fragile X syndrome.
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Gandhi RM, Kogan CS, Messier C. 2-Methyl-6-(phenylethynyl) pyridine (MPEP) reverses maze learning and PSD-95 deficits in Fmr1 knock-out mice. Front Cell Neurosci 2014; 8:70. [PMID: 24701200 PMCID: PMC3965849 DOI: 10.3389/fncel.2014.00070] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Accepted: 02/17/2014] [Indexed: 11/22/2022] Open
Abstract
Fragile X Syndrome (FXS) is caused by the lack of expression of the fragile X mental retardation protein (FMRP), which results in intellectual disability and other debilitating symptoms including impairment of visual-spatial functioning. FXS is the only single-gene disorder that is highly co-morbid with autism spectrum disorder and can therefore provide insight into its pathophysiology. Lack of FMRP results in altered group I metabotropic glutamate receptor (mGluR) signaling, which is a target for putative treatments. The Hebb-Williams (H-W) mazes are a set of increasingly complex spatial navigation problems that depend on intact hippocampal and thus mGluR-5 functioning. In the present investigation, we examined whether an antagonist of mGluR-5 would reverse previously described behavioral deficits in fragile X mental retardation 1 knock-out (Fmr1 KO) mice. Mice were trained on a subset of the H-W mazes and then treated with either 20 mg/kg of an mGluR-5 antagonist, 2-Methyl-6-(phenylethynyl) pyridine (MPEP; n = 11) or an equivalent dose of saline (n = 11) prior to running test mazes. Latency and errors were dependent variables recorded during the test phase. Immediately after completing each test, marble-burying behavior was assessed, which confirmed that the drug treatment was pharmacologically active during maze learning. Although latency was not statistically different between the groups, MPEP treated Fmr1 KO mice made significantly fewer errors on mazes deemed more difficult suggesting a reversal of the behavioral deficit. MPEP treated mice were also less perseverative and impulsive when navigating mazes. Furthermore, MPEP treatment reversed post-synaptic density-95 (PSD-95) protein deficits in Fmr1 KO treated mice, whereas levels of a control protein (β-tubulin) remained unchanged. These data further validate MPEP as a potentially beneficial treatment for FXS. Our findings also suggest that adapted H-W mazes may be a useful tool to document alterations in behavioral functioning following pharmacological intervention in FXS.
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Affiliation(s)
- Réno M Gandhi
- School of Psychology, University of Ottawa Ottawa, ON, Canada
| | - Cary S Kogan
- School of Psychology, University of Ottawa Ottawa, ON, Canada
| | - Claude Messier
- School of Psychology, University of Ottawa Ottawa, ON, Canada
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Wang G, Zhu JJ. DISC1 dynamically regulates synaptic N-methyl-D-aspartate responses in excitatory neurons. Biol Psychiatry 2014; 75:348-50. [PMID: 24507569 DOI: 10.1016/j.biopsych.2013.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 12/12/2013] [Indexed: 11/26/2022]
Affiliation(s)
- Guangfu Wang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia
| | - J Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia.
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Priya A, Johar K, Nair B, Wong-Riley MTT. Specificity protein 4 (Sp4) regulates the transcription of AMPA receptor subunit GluA2 (Gria2). BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1196-206. [PMID: 24576410 DOI: 10.1016/j.bbamcr.2014.02.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 02/14/2014] [Accepted: 02/17/2014] [Indexed: 11/24/2022]
Abstract
The alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are important glutamatergic receptors mediating fast excitatory synaptic transmission in the brain. The regulation of the four subunits of AMPA receptors, GluA1-4, is poorly understood. Excitatory synaptic transmission is highly energy-demanding, and this energy is derived mainly from the oxidative pathway. Recently, we found that specificity factor regulates all subunits of cytochrome c oxidase (COX), a critical energy-generating enzyme. COX is also regulated by nuclear respiratory factor 1 (NRF-1), which transcriptionally controls the Gria2 (GluA2) gene of AMPA receptors. The goal of the present study was to test our hypothesis that Sp-factors (Sp1, Sp3, and/or Sp4) also regulate AMPA subunit genes. If so, we wish to determine if Sp-factors and NRF-1 function via a complementary, concurrent and parallel, or a combination of complementary and concurrent/parallel mechanism. By means of multiple approaches, including electrophoretic mobility shift and supershift assays, chromatin immunoprecipitation, promoter mutations, real-time quantitative PCR, and western blot analysis, we found that Sp4, but not Sp1 or Sp3, regulates the Gria2, but not Gria1, 3, or 4, subunit gene of the AMPA receptor in a concurrent and parallel manner with NRF-1. Thus, Sp4 and NRF-1 both mediate the tight coupling between neuronal activity and energy metabolism at the transcriptional level.
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Affiliation(s)
- Anusha Priya
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Kaid Johar
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Bindu Nair
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Margaret T T Wong-Riley
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
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Lohmann C, Kessels HW. The developmental stages of synaptic plasticity. J Physiol 2014; 592:13-31. [PMID: 24144877 PMCID: PMC3903349 DOI: 10.1113/jphysiol.2012.235119] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 10/16/2013] [Indexed: 01/17/2023] Open
Abstract
The brain is programmed to drive behaviour by precisely wiring the appropriate neuronal circuits. Wiring and rewiring of neuronal circuits largely depends on the orchestrated changes in the strengths of synaptic contacts. Here, we review how the rules of synaptic plasticity change during development of the brain, from birth to independence. We focus on the changes that occur at the postsynaptic side of excitatory glutamatergic synapses in the rodent hippocampus and neocortex. First we summarize the current data on the structure of synapses and the developmental expression patterns of the key molecular players of synaptic plasticity, N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, as well as pivotal kinases (Ca(2+)/calmodulin-dependent protein kinase II, protein kinase A, protein kinase C) and phosphatases (PP1, PP2A, PP2B). In the second part we relate these findings to important characteristics of the emerging network. We argue that the concerted and gradual shifts in the usage of plasticity molecules comply with the changing need for (re)wiring neuronal circuits.
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Affiliation(s)
- Christian Lohmann
- C. Lohmann and H. W. Kessels: The Netherlands Institute for Neuroscience, the Royal Academy of Arts and Sciences, Meibergdreef 47, 1105 BA, Amsterdam, the Netherlands. Emails: ,
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Hayashi T, Yoshida T, Ra M, Taguchi R, Mishina M. IL1RAPL1 associated with mental retardation and autism regulates the formation and stabilization of glutamatergic synapses of cortical neurons through RhoA signaling pathway. PLoS One 2013; 8:e66254. [PMID: 23785489 PMCID: PMC3681934 DOI: 10.1371/journal.pone.0066254] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 05/02/2013] [Indexed: 11/20/2022] Open
Abstract
Interleukin-1 receptor accessory protein-like 1 (IL1RAPL1) is associated with X-linked mental retardation and autism spectrum disorder. We found that IL1RAPL1 regulates synapse formation of cortical neurons. To investigate how IL1RAPL1 controls synapse formation, we here screened IL1RAPL1-interacting proteins by affinity chromatography and mass spectroscopy. IL1RAPL1 interacted with Mcf2-like (Mcf2l), a Rho guanine nucleotide exchange factor, through the cytoplasmic Toll/IL-1 receptor domain. Knockdown of endogenous Mcf2l and treatment with an inhibitor of Rho-associated protein kinase (ROCK), the downstream kinase of RhoA, suppressed IL1RAPL1-induced excitatory synapse formation of cortical neurons. Furthermore, we found that the expression of IL1RAPL1 affected the turnover of AMPA receptor subunits. Insertion of GluA1-containing AMPA receptors to the cell surface was decreased, whereas that of AMPA receptors composed of GluA2/3 was enhanced. Mcf2l knockdown and ROCK inhibitor treatment diminished the IL1RAPL1-induced changes of AMPA receptor subunit insertions. Our results suggest that Mcf2l-RhoA-ROCK signaling pathway mediates IL1RAPL1-dependent formation and stabilization of glutamatergic synapses of cortical neurons.
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Affiliation(s)
- Takashi Hayashi
- Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Tomoyuki Yoshida
- Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Moonjin Ra
- Department of Metabolome, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Ryo Taguchi
- Department of Metabolome, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Masayoshi Mishina
- Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
- Brain Science Laboratory, The Research Organization of Science and Technology, Ritsumeikan University, Kusatsu, Shiga, Japan
- * E-mail:
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Arf6-GEF BRAG1 regulates JNK-mediated synaptic removal of GluA1-containing AMPA receptors: a new mechanism for nonsyndromic X-linked mental disorder. J Neurosci 2012; 32:11716-26. [PMID: 22915114 DOI: 10.1523/jneurosci.1942-12.2012] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Activity-dependent modifications of excitatory synapses contribute to synaptic maturation and plasticity, and are critical for learning and memory. Consequently, impairments in synapse formation or synaptic transmission are thought to be responsible for several types of mental disabilities. BRAG1 is a guanine nucleotide exchange factor for the small GTP-binding protein Arf6 that localizes to the postsynaptic density of excitatory synapses. Mutations in BRAG1 have been identified in families with X-linked intellectual disability (XLID). These mutations mapped to either the catalytic domain or an IQ-like motif; however, the pathophysiological basis of these mutations remains unknown. Here, we show that the BRAG1 IQ motif binds apo-calmodulin (CaM), and that calcium-induced CaM release triggers a reversible conformational change in human BRAG1. We demonstrate that BRAG1 activity, stimulated by activation of NMDA-sensitive glutamate receptors, depresses AMPA receptor (AMPA-R)-mediated transmission via JNK-mediated synaptic removal of GluA1-containing AMPA-Rs in rat hippocampal neurons. Importantly, a BRAG1 mutant that fails to activate Arf6 also fails to depress AMPA-R signaling, indicating that Arf6 activity is necessary for this process. Conversely, a mutation in the BRAG1 IQ-like motif that impairs CaM binding results in hyperactivation of Arf6 signaling and constitutive depression of AMPA transmission. Our findings reveal a role for BRAG1 in response to neuronal activity with possible clinical relevance to nonsyndromic XLID.
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Parasynaptic NMDA receptor signaling couples neuronal glutamate transporter function to AMPA receptor synaptic distribution and stability. J Neurosci 2012; 32:2552-63. [PMID: 22396428 DOI: 10.1523/jneurosci.3237-11.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
At synapses, two major processes occur concomitantly after the release of glutamate: activation of AMPA receptors (AMPARs) to conduct synaptic transmission and activation of excitatory amino acid transporters (EAATs) for transmitter removal. Although crosstalk between the receptors and EAATs is conceivable, whether and how the transporter activity affects AMPAR synaptic localization remain unknown. Using cultured hippocampal and cortical rat neurons, we show that inhibition of glutamate transporters leads to rapid reduction in AMPAR synaptic accumulation and total AMPAR abundance. EAAT inactivity also results in elevated internalization and reduced surface expression of AMPARs. The reduction in AMPAR amount is accompanied by receptor ubiquitination and can be blocked by suppression of proteasome activity, indicating the involvement of proteasome-mediated receptor degradation. Consistent with glutamate spillover, effect of EAAT inhibition on AMPAR distribution and stability is dependent on the activation of parasynaptically localized NR2B-containing NMDA receptors (NMDARs). Moreover, we show that neuronal glutamate transporters, especially those localized at the postsynaptic sites, are responsible for the observed effect during EAAT suppression. These results indicate a role for neuron-specific glutamate transporters in AMPAR synaptic localization and stability.
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41
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Zorumski CF, Izumi Y. NMDA receptors and metaplasticity: mechanisms and possible roles in neuropsychiatric disorders. Neurosci Biobehav Rev 2012; 36:989-1000. [PMID: 22230702 DOI: 10.1016/j.neubiorev.2011.12.011] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/14/2011] [Accepted: 12/22/2011] [Indexed: 02/08/2023]
Abstract
N-methyl-D-aspartate receptors (NMDARs) are key components of neural signaling, playing roles in synaptic transmission and in the synaptic plasticity thought to underlie learning and memory. NMDAR activation can also have neurotoxic consequences contributing to several forms of neurodegeneration. Additionally, NMDARs can modulate neuronal function and regulate the ability of synapses to undergo synaptic plasticity. Evidence gathered over the past 20 years strongly supports the idea that untimely activation of NMDARs impairs the induction of long-term potentiation (LTP) by a form of metaplasticity. This metaplasticity can be triggered by multiple stimuli including physiological receptor activation, and metabolic and behavioral stressors. These latter findings raise the possibility that NMDARs contribute to cognitive dysfunction associated with neuropsychiatric disorders. This paper examines NMDAR metaplasticity and its potential role in cognition. Recent studies using NMDAR antagonists for therapeutic purposes also raise the possibility that metaplasticity may contribute to clinical effects of certain drugs.
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Affiliation(s)
- Charles F Zorumski
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA.
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42
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Selcher JC, Xu W, Hanson JE, Malenka RC, Madison DV. Glutamate receptor subunit GluA1 is necessary for long-term potentiation and synapse unsilencing, but not long-term depression in mouse hippocampus. Brain Res 2011; 1435:8-14. [PMID: 22197030 DOI: 10.1016/j.brainres.2011.11.029] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 11/10/2011] [Accepted: 11/11/2011] [Indexed: 12/01/2022]
Abstract
Receptor subunit composition is believed to play a major role in the synaptic trafficking of AMPA receptors (AMPARs), and thus in activity-dependent synaptic plasticity. To isolate a physiological role of GluA1-containing AMPARs in area CA3 of the hippocampus, pair recordings were performed in organotypic hippocampal slices taken from genetically modified mice lacking the GluA1 subunit. We report here that long-term potentiation (LTP) is impaired not only at active but also at silent synapses when the GluA1 subunit is absent. The GluA1 knockout mice also exhibited reduced AMPAR-mediated evoked currents between pairs of CA3 pyramidal neurons under baseline conditions suggesting a significant role for GluA1-containing AMPARs in regulating basal synaptic transmission. In two independent measures, however, long-term depression (LTD) was unaffected in tissue from these mice. These data provide a further demonstration of the fundamental role that GluA1-containing AMPARs play in activity-dependent increases in synaptic strength but do not support a GluA1-dependent mechanism for reductions in synaptic strength.
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Affiliation(s)
- Joel C Selcher
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
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43
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Fear conditioning occludes late-phase long-term potentiation at thalamic input synapses onto the lateral amygdala in rat brain slices. Neurosci Lett 2011; 506:121-5. [PMID: 22079527 DOI: 10.1016/j.neulet.2011.10.063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 09/08/2011] [Accepted: 10/27/2011] [Indexed: 01/03/2023]
Abstract
Late-phase long-term potentiation (L-LTP) of excitatory synaptic transmission at thalamic input synapses onto the lateral amygdala (T-LA synapses) has been proposed as a cellular substrate for long-term fear memory. This notion is evidenced primarily by previous reports in which the same pharmacological treatments block both T-LA L-LTP and the consolidation of fear memory. In this study, we report that fear conditioning occludes L-LTP at T-LA synapses in brain slices prepared after fear memory consolidation. L-LTP was restored either when synaptic depotentiation was induced prior to L-LTP induction in brain slices prepared from conditioned rats or when brain slices were prepared from conditioned rats that had been exposed to subsequent fear extinction, which is a behavior paradigm known to induce in vivo synaptic depotentiation at T-LA synapses. These results suggest that fear conditioning recruits L-LTP-like mechanisms that are reversible and saturable at T-LA synapses.
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Wang F, Zhu J, Zhu H, Zhang Q, Lin Z, Hu H. Bidirectional control of social hierarchy by synaptic efficacy in medial prefrontal cortex. Science 2011; 334:693-7. [PMID: 21960531 DOI: 10.1126/science.1209951] [Citation(s) in RCA: 364] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Dominance hierarchy has a profound impact on animals' survival, health, and reproductive success, but its neural circuit mechanism is virtually unknown. We found that dominance ranking in mice is transitive, relatively stable, and highly correlates among multiple behavior measures. Recording from layer V pyramidal neurons of the medial prefrontal cortex (mPFC) showed higher strength of excitatory synaptic inputs in mice with higher ranking, as compared with their subordinate cage mates. Furthermore, molecular manipulations that resulted in an increase and decrease in the synaptic efficacy in dorsal mPFC neurons caused an upward and downward movement in the social rank, respectively. These results provide direct evidence for mPFC's involvement in social hierarchy and suggest that social rank is plastic and can be tuned by altering synaptic strength in mPFC pyramidal cells.
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Affiliation(s)
- Fei Wang
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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45
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Hong I, Kim J, Lee J, Park S, Song B, Kim J, An B, Park K, Lee HW, Lee S, Kim H, Park SH, Eom KD, Lee S, Choi S. Reversible plasticity of fear memory-encoding amygdala synaptic circuits even after fear memory consolidation. PLoS One 2011; 6:e24260. [PMID: 21949700 PMCID: PMC3176280 DOI: 10.1371/journal.pone.0024260] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 08/02/2011] [Indexed: 11/18/2022] Open
Abstract
It is generally believed that after memory consolidation, memory-encoding synaptic circuits are persistently modified and become less plastic. This, however, may hinder the remaining capacity of information storage in a given neural circuit. Here we consider the hypothesis that memory-encoding synaptic circuits still retain reversible plasticity even after memory consolidation. To test this, we employed a protocol of auditory fear conditioning which recruited the vast majority of the thalamic input synaptic circuit to the lateral amygdala (T-LA synaptic circuit; a storage site for fear memory) with fear conditioning-induced synaptic plasticity. Subsequently the fear memory-encoding synaptic circuits were challenged with fear extinction and re-conditioning to determine whether these circuits exhibit reversible plasticity. We found that fear memory-encoding T-LA synaptic circuit exhibited dynamic efficacy changes in tight correlation with fear memory strength even after fear memory consolidation. Initial conditioning or re-conditioning brought T-LA synaptic circuit near the ceiling of their modification range (occluding LTP and enhancing depotentiation in brain slices prepared from conditioned or re-conditioned rats), while extinction reversed this change (reinstating LTP and occluding depotentiation in brain slices prepared from extinguished rats). Consistently, fear conditioning-induced synaptic potentiation at T-LA synapses was functionally reversed by extinction and reinstated by subsequent re-conditioning. These results suggest reversible plasticity of fear memory-encoding circuits even after fear memory consolidation. This reversible plasticity of memory-encoding synapses may be involved in updating the contents of original memory even after memory consolidation.
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Affiliation(s)
- Ingie Hong
- School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul, Korea
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46
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Hong I, Kim J, Song B, Park S, Lee J, Kim J, An B, Lee S, Choi S. Modulation of fear memory by retrieval and extinction: a clue for memory deconsolidation. Rev Neurosci 2011; 22:205-29. [PMID: 21476941 DOI: 10.1515/rns.2011.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Memories are fragile and easily forgotten at first, but after a consolidation period of hours to weeks, are inscribed in our brains as stable traces, no longer vulnerable to conventional amnesic treatments. Retrieval of a memory renders it labile, akin to the early stages of consolidation. This phenomenon has been explored as memory reactivation, in the sense that the memory is temporarily 'deconsolidated', allowing a short time window for amnesic intervention. This window closes again after reconsolidation, which restores the stability of the memory. In contrast to this 'transient deconsolidation' and the short-spanned amnesic effects of consolidation blockers, some specific treatments can disrupt even consolidated memory, leading to apparent amnesia. We propose the term 'amnesic deconsolidation' to describe such processes that lead to disruption of consolidated memory and/or consolidated memory traces. We review studies of these 'amnesic deconsolidation' treatments that enhance memory extinction, alleviate relapse, and reverse learning-induced plasticity. The transient deconsolidation that memory retrieval induces and the amnesic deconsolidation that these regimes induce both seem to dislodge a component that stabilizes consolidated memory. Characterizing this component, at both molecular and network levels, will provide a key to developing clinical treatments for memory-related disorders and to defining the consolidated memory trace.
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Affiliation(s)
- Ingie Hong
- School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 151-742, Republic of Korea
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47
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Abstract
The Ras family GTPases (Ras, Rap1, and Rap2) and their downstream mitogen-activated protein kinases (ERK, JNK, and p38MAPK) and PI3K signaling cascades control various physiological processes. In neuronal cells, recent studies have shown that these parallel cascades signal distinct forms of AMPA-sensitive glutamate receptor trafficking during experience-dependent synaptic plasticity and adaptive behavior. Interestingly, both hypo- and hyperactivation of Ras/ Rap signaling impair the capacity of synaptic plasticity, underscoring the importance of a "happy-medium" dynamic regulation of the signaling. Moreover, accumulating reports have linked various genetic defects that either up- or down-regulate Ras/Rap signaling with several mental disorders associated with learning disability (e.g., Alzheimer's disease, Angelman syndrome, autism, cardio-facio-cutaneous syndrome, Coffin-Lowry syndrome, Costello syndrome, Cowden and Bannayan-Riley-Ruvalcaba syndromes, fragile X syndrome, neurofibromatosis type 1, Noonan syndrome, schizophrenia, tuberous sclerosis, and X-linked mental retardation), highlighting the necessity of happy-medium dynamic regulation of Ras/Rap signaling in learning behavior. Thus, the recent advances in understanding of neuronal Ras/Rap signaling provide a useful guide for developing novel treatments for mental diseases.
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Affiliation(s)
- Ruth L Stornetta
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
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Peng Y, Zhao J, Gu QH, Chen RQ, Xu Z, Yan JZ, Wang SH, Liu SY, Chen Z, Lu W. Distinct trafficking and expression mechanisms underlie LTP and LTD of NMDA receptor-mediated synaptic responses. Hippocampus 2010; 20:646-58. [PMID: 19489005 DOI: 10.1002/hipo.20654] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Although an increasing number of studies have demonstrated the plasticity of NMDA receptor-mediated synaptic transmission, little is known about the molecular mechanisms that underlie this neurologically important process. In a study of NMDAR-mediated synaptic responses in hippocampal Schaffer-CA1 synapses whose AMPA receptor (AMPAR) activity is totally blocked, we uncovered differences between the trafficking mechanisms that underlie the long-term potentiation (LTP) and long-term depression (LTD) that can be induced in these cells under these conditions. The LTP-producing protocol failed to induce a change in the amplitude of NMDAR-mediated postsynaptic currents (NMDAR EPSCs) in the first 5-10 min, but induced gradual enhancement of NMDAR EPSCs thereafter that soon reached a stable magnitude. This "slow" LTP of NMDAR EPSCs (LTP(NMDA)) was blocked by inhibiting exocytosis or actin polymerization in postsynaptic cells. By contrast, LTD of NMDAR EPSCs (LTD(NMDA)) was immediately inducible, and, although it was blocked by the actin stabilizer, it was unaffected by exocytosis or endocytosis inhibitors. Furthermore, concomitant changes in the decay time of NMDAR EPSCs suggested that differential switches in NR2 subunit composition accompanied LTP(NMDA) and LTD(NMDA), and these changes were blocked by the calcium buffer BAPTA or an mGluR antagonist. Our results suggest that LTP(NMDA) and LTD(NMDA) utilize different NMDAR trafficking pathways and express different ratios of NMDAR subunits on the postsynaptic surface.
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Affiliation(s)
- Yi Peng
- Department of Neurobiology, Nanjing Medical University, Nanjing, Jiangsu Province, People's Republic of China
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Shouval HZ, Wang SSH, Wittenberg GM. Spike timing dependent plasticity: a consequence of more fundamental learning rules. Front Comput Neurosci 2010; 4. [PMID: 20725599 PMCID: PMC2922937 DOI: 10.3389/fncom.2010.00019] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Accepted: 06/07/2010] [Indexed: 11/13/2022] Open
Abstract
Spike timing dependent plasticity (STDP) is a phenomenon in which the precise timing of spikes affects the sign and magnitude of changes in synaptic strength. STDP is often interpreted as the comprehensive learning rule for a synapse - the "first law" of synaptic plasticity. This interpretation is made explicit in theoretical models in which the total plasticity produced by complex spike patterns results from a superposition of the effects of all spike pairs. Although such models are appealing for their simplicity, they can fail dramatically. For example, the measured single-spike learning rule between hippocampal CA3 and CA1 pyramidal neurons does not predict the existence of long-term potentiation one of the best-known forms of synaptic plasticity. Layers of complexity have been added to the basic STDP model to repair predictive failures, but they have been outstripped by experimental data. We propose an alternate first law: neural activity triggers changes in key biochemical intermediates, which act as a more direct trigger of plasticity mechanisms. One particularly successful model uses intracellular calcium as the intermediate and can account for many observed properties of bidirectional plasticity. In this formulation, STDP is not itself the basis for explaining other forms of plasticity, but is instead a consequence of changes in the biochemical intermediate, calcium. Eventually a mechanism-based framework for learning rules should include other messengers, discrete change at individual synapses, spread of plasticity among neighboring synapses, and priming of hidden processes that change a synapse's susceptibility to future change. Mechanism-based models provide a rich framework for the computational representation of synaptic plasticity.
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Affiliation(s)
- Harel Z Shouval
- Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston Houston, TX, USA
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PKMzeta maintains memories by regulating GluR2-dependent AMPA receptor trafficking. Nat Neurosci 2010; 13:630-4. [PMID: 20383136 DOI: 10.1038/nn.2531] [Citation(s) in RCA: 231] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Accepted: 03/01/2010] [Indexed: 11/08/2022]
Abstract
The maintenance of long-term memory in hippocampus, neocortex and amygdala requires the persistent action of the atypical protein kinase C isoform, protein kinase Mzeta (PKMzeta). We found that inactivating PKMzeta in the amygdala impaired fear memory in rats and that the extent of the impairment was positively correlated with a decrease in postsynaptic GluR2. Blocking the GluR2-dependent removal of postsynaptic AMPA receptors abolished the behavioral impairment caused by PKMzeta inhibition and the associated decrease in postsynaptic GluR2 expression, which correlated with performance. Similarly, blocking this pathway for removal of GluR2-containing receptors from postsynaptic sites in amygdala slices prevented the reversal of long-term potentiation caused by inactivating PKMzeta. Similar behavioral results were obtained in the hippocampus for unreinforced recognition memory of object location. Together, these findings indicate that PKMzeta maintains long-term memory by regulating the trafficking of GluR2-containing AMPA receptors, the postsynaptic expression of which directly predicts memory retention.
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